‘Invasional meltdown’: evidence for unexpected consequences and cumulative impacts of multispecies invasions

W. Ian Montgomery, Mathieu G. Lundy, Neil Reid

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


Empirical support for ‘invasional meltdown’, where the presence of one invading species facilitates another and compounds negative impacts on indigenous species, is equivocal with few convincing studies. In Ireland, the bank vole was introduced 80 years ago and now occupies a third of the island. The greater white-toothed shrew arrived more recently within the invasive range of the bank vole. We surveyed the abundance of both invasive species and two indigenous species, the wood mouse and pygmy shrew, throughout their respective ranges. The negative effects of invasive on indigenous species were strong and cumulative bringing about species replacement. The greater white-toothed shrew, the second invader, had a positive and synergistic effect on the abundance of the bank vole, the first invader, but a negative and compounding effect on the abundance of the wood mouse and occurrence of the pygmy shrew. The gradual replacement of the wood mouse by the bank vole decreased with distance from the point of the bank vole’s introduction whilst no pygmy shrews were captured where both invasive species were present. Such interactions may not be unique to invasions but characteristic of all multispecies communities. Small mammals are central in terrestrial food webs and compositional changes to this community in Ireland are likely to reverberate throughout the ecosystem. Vegetation composition and structure, invertebrate communities and the productivity of avian and mammalian predators are likely to be affected. Control of these invasive species may only be effected through landscape and habitat management.
Original languageEnglish
Pages (from-to)1111-1125
Number of pages15
JournalBiological Invasions
Issue number6
Publication statusPublished - Jun 2012


  • Impacts
  • Interspecific competition
  • Island populations
  • Invasional meltdown
  • Multiple
  • Small mammal community

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology


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